The invention pertains to a device for attaching/firmly holding an exterior covering against an elastic layer type padding with thickness (e) and made of foam attached to the structure of a seat bottom or backrest.
Such a device is meant to press the exterior covering, typically a soft fabric, in such a way that the fabric conforms to the shape of the padding of the backrest or seat and so that there is no area where the exterior covering is taut in relation to the foam when the foam has a concave shape, thus forming an unsightly gap between the taut exterior covering and the foam, because it does not reproduce the actual profile of the backrest.
Until now, this cladding problem has been resolved indirectly by joining different pieces of covering to each other on a same backrest, each piece of covering corresponding to an area of foam having a predefined shape, in such a way that the pieces of covering, once joined to each other, perfectly correspond to the shape given by the foam. In other words, it wasn't a matter of using a single piece of fabric for complex shapes of the backrest. This is especially the case in seat bottoms and backs used in the automotive field. Generally, these pieces of covering are attached by seams and often fastened peripherally by male connectors which can be clipped into female connectors pre-inserted in the foam of the seat or back. The clipping between the male connector and the female connector is thus made inside of the foam, in a hollow region provided for this purpose.
Documents JP 2011156252 and WO 201124675 or US 20080224509 disclose such cladding device, which have the drawback of a fastidious and long implementation given the number of junctions to be made and which are, moreover, not easy because they are made in part blindly within the foam.
The piecing of the exterior covering complicates its attachment to the structure and to the foam and gives an unattractive appearance to the exterior of the seat bottom and backrest. The male connectors and the female connectors are moreover relatively sophisticated components, thus leading to an additional cost to manufacture the seat.
There are also cladding devices made from upholstery buttons. These buttons are also used for the decoration of couches or armchairs. They are composed of a relatively thick head which is visible from the exterior since they are decorative elements, and a shank with a pointed end fitting, so that the button can be stuck into the padded lining of the armchair. A clip is provided so that the buttons cannot be withdrawn from the armchair. Again, it is therefore necessary to have both a male part (the button) and a female part (the clip) in order to be able to firmly hold the covering against the padding of the seat. The documents U.S. Pat. No. 5,214,811, GB 2025558 and U.S. Pat. No. 3,771,199 disclose such upholstery buttons.
These upholstery buttons have the drawback of having a relatively thick and imposing head which can therefore be bothersome to the user's back when he/she leans into the backrest of a seat for example. Moreover, these buttons do not allow the covering to conform to the shape of the padded lining because they heavily compress it when they are clipped. They create compression zones in the armchair, intended to be decorative.